Coal cleaner



. 1, 1942. M. A. KENDALL VEI'AL com CLEANER Filed Oct. 23, 1939 7 Shegts-Sheet l El. EVATUE ELEV/770E M/DDL lNGS HOPPEE 1, 1942. M. A. KENDALL El'AL COAL CLEANER Filed Oct. 23, 1939 7 Sheets-Sheet 2 lfzuen'zors: P017 flfiznaall Chester (ll 00732 Dec. 1, '1942. M. A. KENDALL EI'AL 2,303,367

COAL CLEANER Filed Oct. 23, 1939 7 Sheets-Sheet 5 5 5 P a QQN WWW W 0 0mm m5 n r 0 \Q y B Q av} F. 5 l 1 Q I I HHNIHH ll! NAQ \m R! mm mw \N g Q Qm \w m mm WI r mm .M I s m Q I. I|MMIIIH| r WN g /\1\ M IQ IL .H HHHH m M w wg mw 1, 1942. M. A. KENDALL EFAL COAL CLEANER Filed Oct. 23, 1939 '7 Shets-Sheet 4 M. A. KENDALL ET AL,

COAL CLEANER Filed Oct. 25 1939 '7 Sheets-Sheet 5 Dec. 1, 1942,. M. A. KENDALL ETAL 2,303,367

COAL CLEANER Filed Oct. 23, 1939 7 Sheets-Sheet 6 fiwanzfors: '0 M7 072 A Kama I Chasm?" Cljfaonz 1, 1942. M, A. KENDALL ETI'AL c051, CLEANER Filed Oct. 23, 1939 7 Sheets-Sheet 7 Patented Dec.- 1, 1942 UNITED STATESPATENT OFFICE COAL CLEANER Myron A. Kendall and Chester 0. Moore, Aurora, 111., assignors to Stephens-Adamson MI. 00., a corporation of Illinois 14 Claims.

Coal as it comes from the mine termed "raw coal contains in intermixture, impurities such as slate. rock. and other materials that will not burn and are technically known as refuse. In order to save freight on the refuse and give the customer the maximum heat with the minimum ash, the coal is cleaned" at the mine by separating it from the refuse, or at least reducing the refuse to an allowable percentage of the whole.

The most satisfactory cleaning is done with a dry fluid heavy enoughto float" the coal and light enough to let the rock, etc. sink.

Such cleaning has been carried on for year in accord with the following patents:

Fraser et al., No. 1,534,846, .April 21, 1925; Fraser, No. 1,801,195, April 14, 1931; Fraser, No. 2,007,190, July 9, 1935.

But the apparatus was large, heavy and costly and the rate of cleaning was objectionably slow.

The principal object of this invention is to speed up the cleaning process and reduce the apparatus to a relatively small inexpensive machine that can be made standard or nearly standard construction to suit a great variety of conditions.

The cleaning process is speeded up by feeding the raw coal into a rapidly boiling and flowing stream of sand and air that quickly floats the coal away and drops the heavy refuse to the bottom where it can be' readily withdrawn as fast 1 as it accumulates. Such a stream is produced by feeding sand into a downwardly inclined reciprocating trough and introducing air under pressure through the pervious bottom of the trough into the sand. A separator like that can I have a cleaning capacity of twenty-five to thirty tons of coal per hour per foot of width, as compared with six to eight tons per hour per foot of width in prior apparatus. v wide will do what heretofore required a twelve foot width.

This reduction in size makes it possible to simplify the necessary means for returning the sand and to make use of a small circular elevator.

or sand wheel revolved on supporting rollers with a minimum of work that eliminates complicated and expensive apparatus that heretofore caused most of the trouble in operation and most of the cost of maintenance.

It also fits in with a further improvement inreturning the refuse for further treatment not in the primary cleaning stream but in a separate small stream alongside the primary stream and maintained at small additional expense by the same reciprocating and air supplying means. A

slight increase in width of the elevator provides space for the refuse separate from the returning sand and brings the refuse into position to be fed into the auxiliary treatment stream provided for by a similar slight increase in the width of the reciprocating trough and a lengthwise partition to separate the two streams.

Further objects and advantages of the invention will 'appear as'the description is read in con-.

nection with the. accompanying drawings illustrating a preferred commercial embodiment of the invention, and in which Fig. 1 is a diagrammatic representation of the primary treatment trough and associated parts;

Fig. 2 is a similar diagram of the secondary treatment trough and associated parts; I,

Fig. 3 is a side elevation, with parts broken away, of a standard commercial machine embodying the invention that has been found eminently satisfactory in practice;

illustrating how the reciprocating troughs are A trough four feet mounted on rubber;

Figs. 9 andlO are sectional views through the circular elevator or sand wheel, and associated parts, taken on the lines 99 and l0l0 of Fig. 3;

Fig. 11 is an enlarged longitudinal section 'through the primary treatment trough and assosponding description are used for the purpose of disclosure only and are not intended to impose limitations on the claims, for with this disclosure as a guide those skilled in the art will design other forms embodying the substance of the invention.

(Primary treatment l2 and the trough is given a lengthwise reciprocatingmotion. Sand is fed from the hopper l3 a screen 2|, and the sand shaken out of the coal is fed into a reciprocating return trough 22 by which it is returned to the lower part of the elevator 23 that delivers it back to the hopper l3.

The heavier constituents of the raw coal sink into the fluid sand and air stream. and are withdrawn through discharge chutes 24 and 25, ex-

tending down from the bottom of the primary trough and throttled by relatively stationary valves 26 and 21. The rate of flow through these chutes is regulated by gates 28 and 29, which determines the amount of diversion from the stream in the primary trough. As a rule the diversion and other things will be adjusted to insure that nothing but clean coal is delivered from the desander l9. However, some will be satisfied to have a small percentage of refuse" go over with the coal in order to increase the speed of the treatment. Insuring that only clean coal goes over to the desander l9 will usually mean that some coal passes out through the discharge chutes 24 and with the refuse, either because the coal lumps have adhering particles of slate or other heavy matter or for someother reason, they find their way along with the main volume of the refuse. For that reason the prodv uct taken off from the bottom of the trough will usually be called middlings," to signify that it is neither pure coal nor pure refuse, but COD? tains some of both.

Some operators will want to deliver pure coal only and will make adjustments accordingly, others will want to save all the coal and even, if

necessary, include some refuse and will make ad- 7 justments accordingly.

As a rule, the primary treatment will be with adjustments, delivering clean coal only, further treatment being left to the secondary stage.

The reciprocating motion oi. the chutes relative to the valves 26 and 21 feeds the middlings and sand onto the middlings desander 30, in-

'the gates 40 and 4|.

through the chute 42 under control of any suitable feeder gate. The action is the same as described before, the coal flowing oif with the stream onto the desander iii, the heavier refuse sinking in the stream and being withdrawn through the discharge chutes 36 and 31 under the throttling action of the valves 38 and 39 and The refuse is fed into the refuse desander 43, which includes a screen 44 and a chute 45, also forming a part of the return trough 22 and partaking of its reciprocating motion, whereby the sand is shaken out and the refuse is delivered to a conveyor 46.

The operation is continuous, the sand being circulated and the raw coal being fed into the primary treatment trough, and middlings into the secondary'treatment trough and the clean coal being delivered onto the conveyor 20 and the final refuse being delivered to the conveyor.

This general description gives the main features of the scheme both in the procedure and in the apparatus, the details or which will necessarily be varied to meet personal-preference and particular conditions.

The troughs are preferably made in one and divided by a partition 41 (Figs. 6, 9, 10, 11 and 12 which separates the primary and secondary streams and also separates the air cells I 2 beneath the air pervious bottoms I I.

Air is supplied to the cells |2 through headers 48 running along the sides of the trough and communicating with the cells |2 through openings 49 throttled by the valves 50, having stems 5| projecting above the headers 46. as indicated at 52, to permit adjustment of the individual valves to control and vary the flow of air to the respective cells.

The air peryious bottoms II are preferably made of twelve inch strips of carborundum and for that reason the cells are twelve inches wide and run crosswise to the troughs beneath the cluding the screen 3| and the-chute 32. This desander, being apart of the return trough 22, partakes of its reciprocating motion, sifts out the sand into the trough and delivers the middlings through the chute 32 into the middlings section 33 of the elevator,,which delivers them to the middlings feed hopper 34 (Fig.2).

Secondary treatment In Fig. 2 the secondary treatment trough 35 is shown in every way similar to the primary treatment trough [0 in Fig. 1, and preferably is corresponding carborundum strips. By. this arrangement successive twelve inch lengths, or approximately so, of each trough may be subjected to diflferent air pressures and correspondingly the specific gravity of that portion of the stream may be' varied. As a rule, where the depth of the stream is increased, as over the plates 59, an increase in the volume of air will be appropriate.

Air is supplied to the headers 46 by a tube 53.

(Fig. 6) extending crosswise beneath the troughs and connected at one end by a flexible hose 54 with a compressor 55 (Fig. 3)- taking air through large filters 56 and driven by a motor 51 through a variable speed reduction gearing 56.

Heretofore it has been the practice to run the air compressor at maximum capacity all the while and reduce the pressure in the system by bleeding it to the atmosphere. This means that the driving motor, air compressor and filters work to maximum capacity all the time and waste much energy. By the present arrangement the transmission is adjusted to vary the speed of the compressor to make the supply suited to the' needs at the particular time, thus the motor, compressor and filters never do any extra work, whereby all have a greater period of service at less cost.

Turning to Fig. 11, it will beseen that two sections 53 of the pervious'floor are dropped with respect to the others to make a step down of about one inch and on theright'of each there is an inclined air pervious strip 66 forming one wall of the corresponding discharge chutes 24 and 25.

The exact relation between the first step in the pervious floor and the raw coal feed is a matter of selection depending upon conditions, but the relation shown in Fig. 11 has been found to be very satisfactory for a variety of coal. The feed of the sand and the air together with the reciprocating of the trough has formed a boiling flowing stream running down the trough when V along the bottom. As the latter passes over the step 58 it drops onto the incline 60 and passes easily into the discharge chute 24, swept by air through. the strip 60 which tends to clear it of entrained lighter particles.

The major part of the separation under ordi-. nary circumstances will have been accomplished at this point, and many will be content to omit the remainder of the separating; apparatus. However, there are'conditions underwhich some heavy material will be in the stream after it passes the chute24 and for that reason the stream is extended in the trough to a second step 59, where similar action takes place to insure that practically all material heavier than coal has been taken out of the stream when it passes down the chute i8 onto thed esanding screen it.

The adjustment of the gates 28 and 29 will vary the speed of flow through the discharge As a rule. 40

chutes 24 and 25 to suit conditions. the feed will be right when it permits no accumulation at the entrance of" the chute, though in some instancesa slight accumulation at the entrance of the chute 24 appears tobe ofsome advantage in giving the stream a sort of ripple by which the lighter particles are thrown over and float readily on the top of the stream.

It will be seen in Fig. 11 that the valves 25 and 21 are really troughs composed of a bottom andtwo sides and the bottom is swept by a plate I fastened to and moving with the corresponding chute. a

The feed of middlings and sand from the valves 26, and 21 drops onto inclined plates 6.2, 63, in a forked passage way 64 carried by frame members 65 and open at the bottom to deliver the sand and middlings onto the screen li of the middlings desander. In like manner, the feed from the. similar valves 88 and 39 (Fig. 2) is delivered onto the refuse desanding screen 44 (Fig. 12).

The gates 28 and ii (Fig. 11) regulate the discharge from the chutes 24 and 25. Naturally, the discharge from the former will be much greater than from the latter and the valves will be adjusted accordingly. In the apparatus shown in this embodiment approximately ninety percent (90%) of the heavier ingredients are removed through the chute 24. Some operators will be content at' the separation obtained at this stage separator, whereas that shown is a twostage separator.

The sand is given fluidity by introducing into it a fluid, in this case air under pressure. l'he 7 specific gravity depends upon the proportions of air and sand. The specific gravity must be higher than the coal in order to get the desired flotation. It must be lower than the stone in order to get -the desired sinking of the stone and similar material. The specific gravity of thesand-air fluid must be maintained somewhere between the coal that is to be floated away and the refuse that is to be sunk.

A fluid of the appropriate specific gravity can be maintained by introducing air through the sand from below. If such a fluid is put on an incline it will flow downhill, if the incline is increased beyond the critical point. depending upon the nature of the sand and the proportions of the air to the sand, the stream will run too thin and it will be impossible to control it and maintain a proper depth of the floating and separating medium. It is necessary to have suflicient depth to the stream to float the coal above the sunk residue. How much clearance between floating coal and sunk residue may be a matter of dispute and choice.

Having the fluid stream of appropriate specific gravity. capacityv is determined by the speed with which the floated coal is taken away and the sunk residue is extracted from the bottom. Shaking the trough, as illustrated in the, present embodiment, relates more particularly. to the movement of the sunk residue than to the floating away of the coal, for the reciprocating movement of the trough effects chiefly those things resting upon the bottom or floor of the trough; namely, the sunk residue. The reciprocating movement prevents alarge lump or accumulation of lumps from obstructing the normal flow of the stream as a whole. A large lump or a flatIpiece naturally would tend to cling to the bottom and thus form an obstruction. thus making .the stream'mount over it or flow around, but the reciprocating movement prevents any such stoppage to any detrimental degree.

Just how much slope, just whatproportion of air and sand, just how rapid the reciprocation, how much the throw and whether the movement shall be in one or more planes. are somewhat matters of choice and trial'and' error, depending upon the material to be separated and the condition in which it is found.

In the embodiment here shown the capacity is -rendered very high by making the air-sand stream in the primary trough light and therefore fast, the result is about ninety per cent (90%) separation in the primary trough, the ten per cent (10%) remaining separation in the second- (100%) separatiomcan have a high capacity single-stage machine at less cost and maintenance than the present embodiment.

The sand hopper i3 extends across and feeds sand to both of the troughs, as shown in'Fig. 10, the feed being controlled by a gate i4 (Figs. 1, 2 and 11) though some will prefer to provide separate gates in order to vary the feed to the respecf tivetroughs.

In one corner (the upper left in Flg. 4) the sand hopper II is partitioned off to form the middlings hopper 34, fitted with the feed spout 42 (Figs. 2 and 9).

The hoppers are preferably fixed relatively to The preferred form of elevator is a wheel or rim, including a tread i9, walls 61 (sheets 2.and and transverse inclined, partitions 69 forming, with the tread and side walls, inwardly opening chambers 69, into which material to be elevated is fed at the bottom of the rim and from which it is discharged as the corresponding partitions move across the top, as indicated in Figs. 9 and 10. The slopes for the partitions 69, here shown, is a result of tests on the angle of repose of selected sand (30 to 80 mesh) on itself and on steel. As a result the sand wheel is a distributor as well as an elevator and delivers the sand onto the hopper to give an even distribution all the way across the trough l2 (Fig. u

A partition 10 (Figs. 1 and 2) divides the ele-' vator into a relatively large sand section and a relatively small middlings section.

The rim of the elevator is supported on rollers H and I2 (Figs. 3 and 6) four in number, and it becomes practically balanced. The only difference being the predominance of material being elevated at the left side in Fig. 6, and that represents the major 'portion of the work to be done in driving the elevator.

The drive is from a motor- 13 (Figs. 4 and 6) through a chain 14, reduction gear box 15, thence thro'ugh a chain It, on the shaft 11 of the supporting rollers 12. In order to insure against slipping under all conditions, a drive should be extended fromthe shaft II to the shaft ll for the rollers II, but an illustration is omitted here for It drops into the sand wheel at approximately the bottom, rises as the wheel is rotated, and is distributed from the plates 99 as they pass over which it is delivered to a suitable conveyor or to a flne coal cleaner, as the choice may be.

The left end of the feeder I (Fig. 3) is carried by two links II and the right by shaft 8 I, through eccentric bearings, not shown in detail, but like those appearing at 92 in Fig. 13.

The desanding screen i9 has its left end mounted on pivoted links 99 and its right end on a shaft 84, through the eccentric bearings 92 (Fig. 13).

In this embodiment, the coal feeder I9 and the desanding screen l9 are each inclined at an inclined angle of 7% but this, of course, is a matter of selection, depending upon conditions.

The throw of the eccentrics is three-quarters inch 6%") and-the shafts II and 94 are driven at 450 R. P. M. by individual motors l9 and 98 (Fig. 4) through V-belt drives 91.

The trough II is carried on four links 98 (Fig. 3) and is reciprocated through a connecting rod 99 driven by a crank shaft 99 (Fig. 4) which, in turn, is driven through a V-belt M by a motor 92. In thisembodiment the crank shaft is driven at 200 R.*'P. M. and has a throw of one inch on the connecting rod 89.

The return shaker trough 22 is carried by four links 93 and is reciprocated by a connecting rod '94 driven by the same crank shaft 99 with the crank having a throw of two and one-quarter inches (2%"). The two cranks are opposed, as

indicated in Fig. 4, to give balance.

Incidentally, all of the driving shafts for the reciprocating parts are equipped with counterbalance fly wheels to maintain dynamic balance throughout the machine. a

All of the links 99, 99, "and 93, are connected at each end through rubber bushings, which act in shear under compression. A detail is shown in Figs. 7 and 8, where the bushings appear at 95. surrounding pins 9| and, in turn, are surrounded by bearings 91 into which they. are compressed by washers 99 under the action of nuts 99. A similar connection is made between the eccentrics 82 and the feeder l8 and the screen l9, as indicated in Fig. 13. These rubber connections allow the necessary slight rotative movementjwhile excluding everything in the nature of a wearing surface likely to be damaged by dust and dirt that usually surrounds such machines.. This not only eliminates wear and reduces maintenance, but contributes to a smooththe top, somewhat after the manner illustrated in Fig. 10. From there the sand proceeds down the troughs, through the desanders into the main return shaker trough 22 and back to the sand wheel. Handling the sand in a circuit of this character eliminates the greatest source of difllrated by the desanding screen i9, which is intended to deliver coal to the conveyor 20, and

return only sand to the return shaker trough 22.

Unless the fine material is removed in advance of -the air-sand treatment, it gradually accumulates in the sand isa-disturbing element which is best removed by the sand, an

* operation tobe avoided.

The fine material delivered from the feeder I6 drops into the hopper 19 (Figs. 1 and 3) from ness and a steadiness of operation.

In an endeavor to make the disclosure full and adequate much more has been shown anddescribed than is necessary under many conditions. A much greater detail is given than should be required for those skilled in the art. Selections will be made in great variety according to conditions and personal choice. In some instances a single separator trough with a single discharge chute for refuse will be sumcient'. Also, in some instances, the length or distance between the coal feed andthe refuse discharge chute can be reduced without detriment to the. separation. When the stream in the trough has the proper depth and the proper specific gravity and speed the separation follows so quickly after the coal is fed into the stream that there is almost immediately a floating away of most of the coal and a sinking to the bottom of most of the refuse which latter, if drawn of! promptly, preserves the stream in operating condition with room enough between the traveling clean coal and the nearly stationary refuse to make the operation of high capacity and efliciency.

Air is used in a broad sense and is intended to cover other suitable dry fluids or gases.

We olaim'as our invention:

1. In an air sand separator for lump materials, an inclined primary treatment trough and an inclined secondary treatment trough sideby side, each having an air pervious bottom, means to reciprocate the troughs rapidly and jointly as a unit, means to feed sand into the upper ends of the troughs, means to supply air under pres-.

surethrough the bottoms of the troughs to mane the sand fluid, means to feed lump materials to the upper portion of the fluid sand stream in the primary treatment trough and means to feed refuse from the primary treatment trough to the upper portion of the fluid sand stream in the secondary treatment trough.

2. In an air sand separator for lump materials, an inclined primary treatment trough and an inclined secondary treatment trough side by side, each having an air pervious bottom, means to reciprocate the troughs rapidly and jointly as a unit, means to feed sand into the upper ends of the troughs, means to supply air under pressure through the bottoms of the troughs to make the sand fluid, means to feed lump materials to separate series ofinwardly opening compartments, one series for the sand and one for the refuse.

6. In a separator for lump materials, a primary treatment trough and a secondary treatment trough side by side and inclined lengthwise, means to reciprocate the troughs, means to feed sand into the upper ends of the troughs, means to return sand from the troughs to the feeding means, including a third trough inclined opposite to the first mentioned troughs, and a circular wheel type elevator receiving sand from the third trough.

7. In a, separator for lump materials, a primary treatment trough and a secondary treatment t'rough side by side and inclined lengthwise, means to reciprocate the troughs, means to feed sand into the upper ends of the troughs, means to feed refusefrom the" primary trough to the the upper portion ofthe fluid sand stream inthe .primary treatment trough, means to' feed refuse from the. primary treatment trough to the upper portion of the fluid sand stream in the secondary treatment trough, and means to take sand and refuse from the primary trough to the respective feeding means,.including a circular elevator.

3. In an air sand separator for lump materials, a downwardly inclined trough having an air pervious bottom, means to reciprocate the trough as a unit rapidly, means to feed a stream of sand into the upper end of the trough, means to supply airunder pressure through the bottom of the. trough in sufllcient volume to make the sand fluid whereby it will flow at high speed down the trough, means to feed lump materials into the upper portion of the fluid stream and means to return sand from the trough to the sand feeding means including a circular wheel type elevator opening generally toward the axis and means for delivering the sand from the trough thereto.

4. In an air sand separator for lump materials, a downwardly inclined trough having an air pervious'bottom, means to reciprocate the secondard treatment trough, means to return sand from both troughs to the flrst mentioned feeding means and to take refuse from the primary trough to the second'mentioned feeding means, including a circular rim having inwardly opening compartments.

8. In a separator, inclined primary and secondary troughs side by side," each having a refuse discharge chute from the bottom, means to reciprocate the troughs rapidly and jointly as a unit, means to feed sand to the upper ends of the troughs, means to feed lump materials to the primary trough, a return trough having separate screened compartments receiving refuse and sand from the respective discharge chutes, and an elevator receiving substantially all of the sand and primary refuse from the return trough separately and .delivering, the sand to bothprimary andsecondary troughs and the primary refuse to the secondary trough.

' 9. In a separator, inclined primary and secondary troughs each having a refuse discharge,

a return trough havingseparate refuse receiving trough as a unit rapidly, means to feed a stream of sand into the upper endof the trough, means to supply air under pressure through the bottom of the trough in sufllcient volume. to make the sand fluid whereby it will flow at high speed down chambers below the respective discharges and each having a desander screen, and means for returning the sand to both primary and secondary troughs and the primary refuse to the sec,- ondary trough, including an elevator receiving substantially all of the sand from the return trough and the primary refuse from the chamber below the primary trough.

10. In a separator, inclined primary'and secondary troughs side by side, each having a refuse discharge chute from the bottom, ,means tore- T ciprocate thetroughs rapidly and Jointlyas a unit, means to feed sand to the upper ends of the troughs, means to feed lump materials to the primary trough, a return trough having separate mary treatment trough and a secondary treat to feed refuse from the primary treatment trough to the secondary treatment trough and means to raise sand and refuse from the primary treatment trough to the respective feeding means, in-

cluding a' circular rim having outside tread and screened compartments to receive refuse and sand from the respective discharge chutes, and a wheel type circular elevator divided to form two series of inwardly opening compartments one of which receives substantially all of the sand from the return trough and the other of which receives the primary refuse from the return trough, said "elevator delivering the sand to both primary and secondary troughs and delivering the primary refuse to the secondary trough. I

11. In a separator, inclined primary and secondary troughs each having a refuse discharge, a return trough having separate refuse receiving chambers below the respective discharges and each having a desander screen, and means for returning substantially all'ofthe sand to both primary andsecondary troughs and for delivering the primaryrefuse to, the secondary trough, in-

eluding a wheel type elevator divided in a plane generally perpendicular to the axis to form two series of inwardly opening compartments one of which receives substantially all of the sand from the return trough and the other of which receives the primary refuse from the chamber below the discharge for the primary trough.

12. In an air sand separator for lump materials, a downwardly inclined trough having a substantially flat air-pervicus bottom capable of supporting sand and disposed substantially in a plane, means to cause a stream of sand to ilow rapidly down the trough including means for feeding sand to the upper end of the trough, means for forcing air up through the pervicus bottom and through the sand. means for rapidly reciprocating the trough in.a direction having an upward and forward component relative .to the bottom, means for supply a mixture of light and heavy lump material on top of the stream at an upper portion thereof, an outlet for the lower stratum in the trough including the heavy material, and discharge means for the re maining strata in the trough, with said trough being substantially unobstructed above said plane to permit said remaining strata to flow rapidly and freely by gravity away from the point at which the strata are separated, the reciprocation of said trough being in a direction to aid the movement of the heavier material on the pervicus bottom toward the outlet for the lower stratum,

and the parts being so related and arranged as to maintain the proportion of sand to lump material high enough to produce in the stream a thick intermediate stratum that is mainly sand.

13. In an air sand separator for lump materials, a trough having a downwardly inclined air-pervicus bottom capable of supporting'sand. means to cause a stream of sand to flow rapidly down the trough including means for feeding copious sand at an upper portion of the trough, means for forcing air up through the pervicus to the inclined bottom, means for supp ying a mixture of light and heavy lump materials to the stream at an upper portion thereof, an outlet for the lower stratum in the trough including the heavy material arranged to draw 01! said stratum together with a substantial amount of sand sub-- stantially without interrupting their movement whereby the-upper surface of the lower stratum slopes downwardly substantially in a plane to the lower end thereof to facilitate the rapid ilow oi the remaining strata thereon, and discharge means for the remaining strata in the trough, with said trough being substantially imobstructed above said plane beyond the draw-oi! point to permit said remaining strata to flow rapidly and freely by gravity away from the point at which the strata are separated, the reciprocation of said trough being in a direction to aid the movement of the heavier material on the pervicus bottom toward the outlet for the lower stratum and the parts being so related and arranged as to maintain the'proportions of sand to lump material high enough to produce in the stream a thick intermediate stratum that is mainly sand.

14. In an air sand separator for 'lump materials, a downwardly inclined trough having an air-pervicus bottom, means to feed a stream of sand into the upper end of the trough, means to supply air under pressure througlrthe bottom of the trough in suiilcient volume to make the sand fluid and create a fluid stream flowing down the trough, means to feed lump material into the upper portion of-the fluid stream, means to re-' eiprocate the trough as a unit to convey downwardly lumps resting on its bottom, and means to separate sand from the lump material delivered from the trough and to return said sand to the sand feeding means including a return trough sloping in a direction opposite to the first named trough, and a circular wheel-type elevator, opening generally toward the axis, receiving sand from the return trough and delivering it to the bottom and through the sand, means for rapidly reciprocating the trough with a motion having a component which is upward and forwardrelative feeding means.

MYRON A. KENDAIL. CHESTER. C. MOORE. 

